Employee Benefits and Incentive Plans - Summary of Stock Option Activity under 2006 EIP and 2013 LTIP (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock granted	(17,168)
Number of Options, Granted	0
Number of Options, Exercised	(413,008)	(112,216)	(218,872)
2006 EIP and 2013 LTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Available for Grant, Beginning Balance	6,278,516
Options Available for Grant, Options granted	0
Options Available for Grant, Options exercised	0
Restricted stock granted	(645,568)
Restricted stock canceled	198,839
Options Available for Grant, Ending Balance	5,868,283	6,278,516
Number of Options, Beginning Balance	2,954,227
Number of Options, Granted	0
Number of Options, Exercised	(400,592)
Number of Options, Ending Balance	2,280,030	2,954,227
Weighted Average Exercise Price, Beginning Balance	$ 27.05
Weighted Average Exercise Price, Granted	0
Weighted Average Exercise Price, Exercised	24.65
Weighted Average Exercise Price, Ending Balance	$ 27.08	$ 27.05
2013 LTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Available for Grant, Options Canceled or forfeited	36,496
Number of Options, Options Canceled or forfeited	(36,496)
Weighted Average Exercise Price, Canceled or forfeited	$ 23.93
2006 EIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Options, Options Canceled or forfeited	(237,109)
Weighted Average Exercise Price, Canceled or forfeited	$ 31.32